it'd been mentioned that the pinacle of swordsmanship is to cut what you wants to cut depending on it's breath
the pinnacle of swordsmanship is to either "cut" or "not cut". there is no distinction between breaths here.
Zoro mentiones the breath of Daz steel specifically, but he also applies BOAT to rocks and leaves.
we now know that the technique Zoro used to cut Daz was CoA haki. CoA haki also does not care which breath the target has.
its either cut or not. no matter what the target.
that still does not mean that a (haki) strike with the intention to cut is guaranteed to work. or else swordsman could just shear through their opponents weapons or any other form of defense at will. this clearly is not happening.